AGITATION NUMERICAL PROBLEMS 1. Let us calculate the mechanical power consumption in a vessel with non-proximity flat blade turbine agitator, without baffles. Geometry of the vessel: D = 1200 mm H = 1200 mm d = 400 mm h = 400 mm Rotational speed of the impeller: n = 6 rev/s Liquid properties: ρ = 860 kg/m 3 (density) µ = 30 cP = 30x10 -3 Pas (viscosity) 2. Let us calculate the mechanical power consumption in a vessel with non-proximity flat blade turbine agitator (6 blades) a. without baffles b. with 4 baffles Geometry of the vessel: D = 1200 mm H = 1200 mm d = 400 mm h = 400 mm w = 80 mm δ = 100 mm Rotational speed of the impeller: n = 500 rev/min Liquid properties: ρ = 1180 kg/m 3 (density of glycerine) µ = 12x10 -3 Pas (viscosity)
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AGITATION NUMERICAL PROBLEMS 1.Let us calculate the mechanical power consumption in a vessel with non-proximity flat blade turbine agitator, without baffles. Geometry of the vessel: D = 1200 mm H = 1200 mm d = 400 mm h = 400 mm Rotational speed of the impeller: n = 6 rev/s Liquid properties: = 860 kg/m3 (density) = 30 cP = 30x10-3 Pas (viscosity) 2.Let us calculate the mechanical power consumption in a vessel with non-proximity flat blade turbine agitator (6 blades) a.without baffles b.with 4 baffles Geometry of the vessel: D = 1200 mm H = 1200 mm d = 400 mm h = 400 mm w = 80 mm = 100 mm Rotational speed of the impeller: n = 500 rev/min Liquid properties: = 1180 kg/m3 (density of glycerine) = 12x10-3 Pas (viscosity) 3.What is the power requirement of a 6-blade-turbine 400 mm in diameter? Geometry of the vessel: D = 1200 mm H = 2 m H0 = 1.2 m h = 400 mm w = 8 mm Rotational speed of the impeller: n = 540 rev/min Liquid properties: = 950 kg/m3 (density) = 15 P = 1.5 Pas (viscosity) 4.A tank 1.2 m in diameter and 2 m high is filled to a depth of 1.2 m with a latex having a viscosity of 10 P and a density of 800 kg/m3. The tank is not baffled. A three-blade 360mmdiameterpropellerisinstalledinthetank360mmfromthebottom.The motoravailabledevelops8kW.Isthemotoradequatetodrivethisagitatorata speed of 800 r/min? 5.What power is required for the mixing operation of Prob.4. if a propeller 400 mm in diameterturningat15r/sisusedandiffourbaffles,each120mmwide,are installed? 6.WhatisthemaximumspeedatwhichtheagitatorofthetankdescribedinProb.4. may be driven if the liquid is replaced by one having a viscosity of 1 P and the same density? 7.A disk turbine with six flat blades is installed centrally in a vertical baffled tank 2 m in diameter.Theturbineis0.67mindiameterandispositioned0.67mabovethe bottom of the tank. The turbine blades are 134 mm wide. The tank is filled to a depth of 2 m with an aqueous solution of 50 % NaOH at 65C, which has a viscosity of 12 cP and a density of 1500 kg/m3. The turbine impeller turns at 90 r/min. What power will be required? 8.The agitation system of Prob.7. is to be used to mix a rubber-latex compound having a viscosity of 120 Pas and a density of 1120 kg/m3. What power will be required? Power number (NP) versus Re for baffled vessels mversus Re for unbaffled vessels NPversus Re for unbaffled vessels
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